Skim is a PDF reader and note-taker for OS X. It is designed to help you read and annotate scientific papers in PDF, but is also great for viewing any PDF file. Skim requires Mac OS X 10.6 or higher.
- Viewing PDFs
- Adding and editing notes
- Highlighting important text, including one-swipe highlight modes
- Making "snapshots" for easy reference
- Navigation using table of contents or thumbnails, with visual history
- View all your notes and highlights
- Convenient reading in full screen
- Giving powerful presentations, with built-in transitions
- Handy preview of internal links
- Focus using a reading bar
- Magnification tool
- Smart cropping tools
- Extensive AppleScript support
- Saving passwords in Keychain
- Export notes as text
- Automatic download of remote PDFs
- Support for Apple Remote Control
- Interaction with LaTeX, SyncTeX, and PDFSync
- Integration with BibDesk and other third party applications
- Spotlight support
- Highly customizable
- And much more...
Skim doesn't have basic measuring tools for drawings, so I'm rating features as poor. It also has a limited help function - it took me a while to figure out that when I opened it, it sits on the task bar but doesn't open a programme window; it waits for me to use Finder to open a file. So I'm also marking it down for not conforming to usual usability modes. However it does look quite pretty and seems to have the basic text markup tools, slightly more than are offered by OSX's Preview application. PS To the user who requested coloured notes... OSX's Preview app offers that.
this is a brilliant app, but use is seriously hampered by the inability to drag to select multiple freehand annotations - makes editing these annotations very tiresome. In addition it would be great to have an eraser tool.